Multi-spindle CNC lathe

ABSTRACT

A multi-spindle CNC lathe comprises a frame assembly mounted on a base and including spaced apart, rigidly interconnected subframes defining spaced, parallel alignment surfaces. A plurality of spindles each includes a collet for rotating a stock about a spindle axis. An indexing mechanism positions the spindles in alignment worth with stations located at equally spaced intervals about a central axis. Internal tool slides mounted on the alignment surface of one of the subframes each comprise a servo mechanism for advancing and retracting a cutting tool along a work station axis. External tool slides mounted on the alignment surface of the other subframe each comprise a first servo mechanism for advancing and retracting a cutting tool toward and away from the work station axis and a second servo mechanism for selectively moving the cutting tool back and forth along a path extending parallel to the work station axis.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation application under 37 C.F.R. §1.60 ofapplication Ser. No. 09/285,595 filed Apr. 1, 1999, currently pending,which is a continuation application of application Ser. No. 09/044,353filed Mar. 19, 1998, abandoned, which is a continuation application ofapplication Ser. No. 08/869,047, filed Jun. 4, 1997, now U.S. Pat. No.5,918,514, which is a continuation application of application Ser. No.08/514,734, filed Aug. 14, 1995, now U.S. Pat. No. 5,676,030.

TECHNICAL FIELD

[0002] This invention relates generally to machine tools, and moreparticularly to a multi-spindle CNC lathe that is particularly adaptedfor use in conjunction with JIT and SPC manufacturing philosophies.

BACKGROUND AND SUMMARY OF THE INVENTION

[0003] Machine tools, including drills, lathes, milling machines,grinders and other finishing machines, and more complex devices such asscrew machines, are all characterized by a common objective: themanufacture of large numbers of identical finished parts underconditions of extreme accuracy and maximum economy. As such, interest inand development of machine tools has paralleled the advance of theindustrial revolution.

[0004] Traditionally, machine tools were operated by machinists who wereamong the most highly skilled and the most highly paid of all workers.More recently, however, machine tools have been adapted to a procedureknown as computer numeric control, or CNC, whereby the operation ofmachine tools is regulated by computers or other programmablecontrollers. In accordance with the CNC technique, the dimensions,surface finishes, and other characteristics of the part to bemanufactured are supplied in the form of sequential operatinginstructions which are utilized by the CNC device to regulate theoperation of the machine tool. This allows the completion of finishedparts with more uniformity and more rapidity than has ever been possibleheretofore.

[0005] The adaptation of single spindle lathes, milling machines, andsimilar devices to CNC techniques has largely been successful. However,in the case of multi-spindle machine tools, previous attempts atautomation have largely comprised adapting the cams, gears, and othercomponents comprising such machines to servo control. Perhaps becausethe approach has been one of adapting old designs to new techniques, theeffort to date at automating the operation of multi-spindle lathes bymeans of CNC operation has largely been unsuccessful.

[0006] The present invention comprises a multi-spindle lathe which isentirely adapted for CNC operation. In accordance with the broaderaspects of the invention, a plurality of spindles are positioned atspaced points about a central axis. Each spindle has a collet whichreceives a length of stock and rotates the stock about a spindle axis.An indexing mechanism is provided for selectively positioning thespindles at work stations located at equally spaced points about thecentral axis.

[0007] Each work station comprises an internal tool slide adapted toreceive a cutting tool and to advance the cutting tool toward and awayfrom the rotating stock under the action of a servo mechanism. Anexternal tool slide is also provided for each work station and isadapted to advance a cutting tool both toward and away from and parallelto the axis of rotation of the stock. At each work station the stock isturned rather than formed, meaning that the cutting tools of theindividual work stations maybe utilized to perform a variety of quitedistinct machining operations.

[0008] The multi-spindle CNC lathe of the present invention is readilyadapted for use in conjunction with both the Just In Time (JIT) and theStatistical Process Control (SPC) manufacturing philosophies. Inaccordance with JIT, only the exact number of piece parts necessary tocomplete a particular assembly operation are ordered at any one time.This eliminates the investment in inventory which is necessary whenlarge numbers of piece parts are ordered simultaneously, and alsoeliminates the possibility that previously ordered parts will becomeobsolete due to a change in design. The machine tool of the presentinvention is adapted to JIT because the economic batch is smaller. Thisis because machine tools incorporating the invention do not require thechanging of the cutting tools utilized at the various work stations inorder to change the nature of the piece parts being manufactured, andbecause set up time is reduced dramatically.

[0009] In accordance with SPC, completed piece parts are compared with apredetermined standard with a view towards maintaining the dimensions ofeach part at the center of the tolerance range. If the dimensions of theparts being manufactured begin to vary from the center of the tolerancerange, due to cutting tool wear or otherwise, adjustments in themanufacturing process are immediately instituted in order to maintaintolerances. SPC is easily practiced in the machine tool of the presentinvention since all of the cutting tools are positioned by servomechanisms which are in turn under computer numeric control.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A more complete understanding of the invention may be had byreference to the following Detailed Description, when taken inconjunction with the accompanying Drawings wherein:

[0011]FIG. 1 is a front view of a multi-spindle CNC lathe incorporatingthe present invention;

[0012]FIG. 2 is a front view of the base of the multi-spindle CNC latheof FIG. 1 in which certain parts have been broken away more clearly toillustrate certain features of the invention;

[0013]FIG. 3 is a top view of the base of FIG. 2;

[0014]FIG. 4 is a longitudinal sectional view illustrating the frame andcertain operating components of the multi-spindle CNC lathe of FIG. 1;

[0015]FIG. 5 is an enlargement of a portion of FIG. 4;

[0016]FIG. 6 is a front view of the multi-spindle CNC lathe of thepresent invention similar to FIG. 1 in which the covers of the apparatushave been removed;

[0017]FIG. 7 is an illustration of certain components of themulti-spindle CNC lathe of FIG. 6 taken along the lines 7-7 of FIG. 6;

[0018]FIG. 8 is an illustration of certain components of themulti-spindle CNC lathe of FIG. 6 taken along the line 8-8 in FIG. 6;

[0019]FIG. 9 is an enlargement of a portion FIG. 8;

[0020]FIG. 10 is a further illustration of certain components shown inFIG. 9;

[0021]FIG. 11 is a side view of one of the internal slide assemblies ofthe multi-spindle CNC lathe of FIG. 6 in which certain components havebeen broken more clearly to illustrate certain features of theinvention;

[0022]FIG. 12 is an illustration of certain components of themulti-spindle CNC lathe of FIG. 6 taken along the line 12-12 of FIG. 6;

[0023]FIG. 13 is an illustration of one of the external slide assembliesof the multi-spindle CNC lathe of the present invention;

[0024]FIG. 14 is a sectional view taken along the line 14-14 of FIG. 13;

[0025]FIG. 15 is a sectional view taken along the line 15-15 of FIG. 14further illustrating the external slide assemblies of the multi-spindleCNC lathe of the present invention;

[0026]FIG. 16 is longitudinal sectional view further illustrating theexternal slide assemblies of the multi-spindle CNC lathe of the presentinvention;

[0027]FIG. 17 is a sectional view taken along the line 17-17 of FIG. 13;

[0028]FIG. 18 is an enlargement of a certain portion of the apparatusillustrated in FIG. 17;

[0029]FIG. 19 is an illustration of certain of the components of themulti-spindle CNC lathe of the present invention taken along the line19-19 of FIG. 6.

[0030]FIG. 20 is an illustration of one of the spindles of themulti-spindle CNC lathe of the present invention showing the componentparts thereof in a first orientation;

[0031]FIG. 21 is view similar to FIG. 20 showing the component parts ofthe spindle in a second orientation;

[0032]FIG. 22 is an illustration similar to FIG. 20 showing thecomponent parts thereof in a third orientation;

[0033]FIG. 23 is a sectional view illustrating the glut actuator of themulti-spindle CNC lathe of the present invention;

[0034]FIG. 24 is as sectional view taken along the line 24-24 of FIG. 25and illustrating the spindle carrier of the multi-spindle CNC lathe ofthe present invention;

[0035]FIG. 25 is an end view of the spindle carrier of the multi-spindleCNC lathe of the present invention;

[0036]FIG. 26 is an enlarged illustration of one of the castingscomprising the frame of the present invention;

[0037]FIG. 27 is illustration of the one of the stock carrying tubes ofthe multi-spindle CNC lathe of the present invention;

[0038]FIG. 28 is an enlarge sectional view of further illustrating thestock carrying tubes of the multi-spindle CNC lathe of the presentinvention;

[0039]FIG. 29 is a front view illustrating the stock carriage assemblyof the multi-spindle CNC lathe of the present invention;

[0040]FIG. 30 is a partial sectional view illustrating the indexingmechanism of the multi-spindle CNC lathe of the present invention;

[0041]FIG. 31 is a partial sectional view illustrating a tool holderaccessary useful in conjunction with the multi-spindle CNC lathe of thepresent invention;

[0042]FIG. 32 is a further illustration of the three point mountingsystem of the frame of the multi-spindle CNC lathe of the presentinvention;

[0043]FIG. 33 is a still further illustration of the three pointmounting system of the frame of the multi-spindle CNC lathe of thepresent invention;

[0044]FIG. 34 is a perspective view illustrating the operation of themulti-spindle CNC lathe of the present invention; and

[0045]FIG. 35 is a perspective view further illustrating the operationof the multi-spindle CNC lathe of the present invention.

DETAITLED DESCRIPTION

[0046] Referring now to the Drawings, and particularly to FIG. 1thereof, there is shown a multi-spindle CNC lathe 50 incorporating thepresent invention. The lathe 50 includes a base 52 which also serves asan coolant reservoir. A housing 54 extends upwardly from the base 52 andserves to enclose and protect both the mechanical components and theproduction components of the multi-spindle CNC lathe 50.

[0047] A computer numeric control (CNC) system 56 is located at one endof the housing 54. The CNC system 56 is preferably of the type sold byGeneral Electric Company as and identified by that company as the PowerMate Motion Control Systems, and may include a computer monitor screen58 and/or a plurality of status lights 60. A keyboard 62 may be used toeffect computer control over the operation OL the lathe 50. The CNC unit56 may further include a conventional control panel 64.

[0048] The housing 54 of the multi-spindle CNC lathe 50 further includesa sliding access door 66. The door 66 is slidably supported on aslideways 68 and is provided with a viewing window 70. The productioncomponents of the multi-spindle CNC lathe 50 are located behind the door66 when it is in the closed potion as illustrated in FIG. 1, and areobservable through the viewing window 70 thereof.

[0049] A hinged door 72 provides access to the mechanical components ofthe lathe 50. Access ports 74 are normally enclosed by removable covers76. A cover 78 enclosing the stock carriers of the lathe 50 extendsleftwardly (FIG. 1) from the main portion of the housing 54.

[0050] Referring now to FIGS. 2 & 3, the base 52 of the multi-spindleCNC lathe 50 is shown in greater detail. The base 52 is comprisedentirely of steel plates which are interconnected by welding. The base52 is provided with a plurality of mounting blocks 80 and a plurality ofmounting holes 82 which function to attach the operating components ofthe lathe 50 to the base 52.

[0051] In addition to supporting and locating the operating componentsof the lathe 50, the base 52 serves as an coolant reservoir. Coolantentering the base 52 is initially contained by a plate 84 which definesa coolant level 86. Chips caused by operation of the multi-spindle CNClathe 50 enter the base 52 through a port 88 and are received on a chipconveyor 90 located above the plate 84. The conveyor 90 transports thechips out of the base 52, where upon the chips fall into a chipreceiving container 92 under the action of gravity.

[0052] During operation of the lathe 50, coolant constantly flows over alip 94 located at one end of the plate 84. From the lip 94 the coolantflows into and through a basket 96 which functions to strain thecoolant, thereby removing any debris which is not transported out of thebase 52 by the chip conveyor 90. Preferably, two baskets 96 are employedin the operation of the lathe, one located in the working position asdefined by a bracket 98 and the other positioned on a drain platform 100which allows coolant to drain out of the basket 96 prior to the removalof debris therefrom. Coolant flowing through the basket 96 located inthe working position as defined by the bracket 98 flows along a pathdefined by the arrows 102 and is returned to the operating components ofthe lathe 50 by a pump (not shown) which withdraws the coolant from thebase at aperture 103. This flow path maintains uniform temperature ofthe base 52 and eliminates static spots which can cause the coolant tobecome rancid.

[0053] As is best shown in FIG. 4, the multi-spindle CNC lathe 50includes a frame 104 comprising an important feature of the invention.The frame 104 include precision castings 106 and 108 which function tosupport and align the operating components of the lathe 50. The casting106 comprises opposed walls 110 and 112, and the casting 108 comprisesopposed walls 114 and 116.

[0054] The walls 110 and 112 of the casting 106 define opposed surfaces120 and 122, respectively. The surfaces 120 and 122 are ground flat andsmooth utilizing Blanchard grinding or a functionally equivalentprocess. The same procedure assures precise parallelism between thesurfaces 120 and 122. The walls 114 and 116 comprising the casting 108defined opposed surfaces 124 and 126 which are identically processed,and are therefore equally flat, smooth, and parallel. The surfaces 122and 124 define the alignment surfaces of the frame 104 of the lathe 50.

[0055] The frame 104 further comprises four tie rods 128 which are matchmachined in order to maintain precise parallelism between the surface122 of the casting 106 and the surface 124 of the casting 108. Each tierod 128 includes an elongate central portion 130 extending to reduceddiameter portion 132 which in turn extends to a threaded end member 134.At the bottom of the casting 108, a bushing 136 is mounted on eachreduced diameter portion 132 and is received in aligned apertures 138formed in the casting 108 and an aperture 140 formed in a mounting block142.

[0056] A plurality of nuts 144 are each threadedly engaged with athreaded end portion 134 of one of the tie rods 128. The nuts 144 engagewashers 146 which in turn engage compression members 148. Thus, uponprecise tightening of the nuts 146, using, for example, a torque wrench,the castings 106 and 108 comprising the frame 104 are securelypositioned with respect to one another.

[0057] At the upper ends of the castings 106 and 108, and at the lowerend of the casting 106, the reduced end portions of the rods 128 extendthrough apertures 138′ formed in the castings 106 and 108. Likewise, thenuts 144 engage the washers 146 which directly engage the castings 106and 108.

[0058] The casting 106 is supported on a mounting block 142′ whichbridges across the frame 52 and is supported by the mounting blocks 80thereof.

[0059] The mounting blocks 142 and 142′ are secured to the base 52 byplurality of threaded fasteners 152. The mounting blocks 142 engage themounting blocks 80 of the base 52 to precisely position the frame 104with respect thereto. An important aspect of the present inventioncomprises the use of the three point mounting system comprising the twomounting blocks 142 and 142′ to mount the frame 104 on the base 52. Bythis means any possibility of tipping, wobbling, or misalinement betweenthe base 52 and the frame 104 is eliminated.

[0060] The three point mounting system which supports the frame 104 onthe base 52 is further illustrated in FIGS. 32 and 33. Each mountingblock 142 engages an individual mounting block 80 of the base 52 tosupport the casting 108 at two parts. In contrast, the mounting block142′ bridges between two mounting blocks 80 and supports the casting 106at a single, central point, thereby providing three point support forthe frame 104. A pin 150 extends through aligned apertures 138 in thecasting 106, and an aperture 104 formed in the center of the mountingblock 142′. A nut 144 is threadably engaged within the end portion 134of the pin 150, and engages a washer 146 which engages a correspondingmember 148.

[0061] A spindle drive motor 154 is mounted at one end of the frame 104of the multi-spindle CNC lathe 50. The spindle drive motor is preferablya variable speed alternating current electric motor. The motor 154 issupported by a motor mounting adaptor 156 which is in turn supported bya bearing housing 158. The bearing housing 158 is secured to the wall110 of the casting 106 of the frame 104 by a plurality of threadedfasteners 160.

[0062] The motor 154 has an output shaft 162 which extends to a flexiblecoupling 164. The flexible coupling 164 in turn drives a spindle driveshaft 166. The drive shaft 166 is rotatably supported by a bearing 168which is retained in the bearing housing 158 by an end plate 170 that isin turn secured by threaded fasteners 172. A spacer 174 and a lock nut176 complete the drive shaft/bearing assembly.

[0063] Referring to FIGS. 4 and 5, the drive shaft 166 extends through apiston 180 which is secured to a tubular ram 182 by a plurality ofthreaded fasteners 183. The piston 180 is mounted in a cylinder 184which is located relative to the wall 112 of the casting 106 by ahardened precision dowel pin 186 and is secured to the wall 112 by aplurality of threaded fasteners 188. A first hydraulic fluid chamber 190is defined at one end of the piston 180 and is isolated by a pluralityof seals 192. The chamber 190 is closed by an end plate 194 which issecured to the cylinder 184 by a plurality of threaded fasteners 196.The end plate 194 is provided with a hydraulic fluid inlet and outletport 198.

[0064] A second hydraulic fluid chamber 200 is located at the oppositeend of the piston 180 and is isolated by a plurality of seals 202. Thechamber 200 is provided with a hydraulic fluid inlet and outlet port 204formed in the cylinder 184. Thus, upon selective application ofhydraulic pressure to one of the chambers 190 or 200 and thesimultaneous release of hydraulic pressure from the opposite chamber,the piston 180 and the tubular ram 182 are caused to move longitudinallyrelative to the cylinder 184.

[0065] The end of the tubular ram 182 remote from the piston 180 isprovided with a flange 206. A retaining ring 208 engages the flange 206,and a plurality of threaded fasteners 210 secure the retaining ring toan adapter 212. The adapter 212 supports a bearing 216 which rotatablysupports the shaft 166. The threaded fasteners 210 and the retainingring 208 also function to secure the tubular ram 182 to a spindlecarrier assembly 218.

[0066] The working components of the multi-spindle CNC lathe 50illustrated in FIGS. 6 through 19, inclusive. As is clearly shown, forexample, in FIGS. 7, 8, and 9, the particular multi-spindle CNC lathe 50illustrated in the Drawings and described herein comprises an eightspindle device. However, as will be appreciated by those skilled in theart, the present invention is readily adapted for use in conjunctionwith multi-spindle CNC lathes having any desired number of spindles asmay be dictated by the requirements of a particular application of theinvention.

[0067] Internal slide assemblies 220 comprising the multi-spindle CNClathe 50 are illustrated in FIGS. 7, 8, 9, 10, and 11, inclusive.Referring particularly to FIGS. 7 and 11, each internal slide assembly220 includes a motor 224 which is secured to a motor mounting plate 226by a plurality of threaded fasteners 228. The motor mounting plate 226is in turn secured to a mounting plate 230 by a plurality of threadedfasteners 232. The mounting plate 230 is in turn secured to the wall 110of the casting 106 comprising the frame 104 by a plurality of threadedfasteners 234.

[0068] The motor 224 has an output shaft 236 which is secured to a drivepulley 238. A drive belt 240 extends around the drive pulley 238 and adriven pulley 242. The driven pulley 242 is mounted on a spacer 244which is in turn secured to an adapter 246. Thus, upon operation of themotor 224, the adapter 246 is rotated under the action of the motor 224,the output shaft 236, the drive pulley 238, the belt 240, the drivenpulley 242, and the spacer 244.

[0069] The adapter 246 is rotatably supported on the plate 110 bybearings 248. The bearings 248 are supported in a bearing housing 250 bya plurally of threaded fasteners 252 which extend through the mountingplate 230. A ball nut 254 is mounted on the adapter 246 and is securedthereto by a plurality of threaded fasteners 256.

[0070] A ball screw 258 extends through and is operatively engaged withthe ball nut 254. The ball screw 258 is secured against rotationrelative to the ball nut 254. Thus, upon actuation of the motor 224 torotate the adapter 246 and the ball nut 254, the ball screw 258 isselective extended or retracted.

[0071] A target adapter 260 extends from one end of the ball screw 258and supports a target 262. A sensor bracket 264 is secured to themounting plate 226 by a plurality of threaded fasteners 266. Proximitysensors 268, 270, and 272 are mounted on the bracket 264. Upon thealignment of the target 262 therewith, the proximity sensors 268, 270,and 272 are actuated to generate a signal indicative of the positioningof the ball screw 258 relatively to the frame 104 of the lathe 50.Proximity sensor 270 is indicative of the normal positioning of the ballscrew 258, proximity sensor 270 is indicative of the fully retractedpositioning of the ball screw 258, and proximity sensor is indicative ofthe fully extended position of the ball screw 258.

[0072] The motor 224 operates under control of the CNC system 54 toposition the ball screw 258. The outputs of the proximity sensors 268,270, and 272 are directed to the CNC system 54, which in turn operatesthe motor 224 to properly position the ball screw 258 in accordance withthe program being run.

[0073] The ball screw 258 extends through a ball screw boot 274. Theboot 274 is secured to the wall 112 of the casting 106 of the frame 104by a plurality of threaded fasteners 276. At the distal end of the boot274 there is provided a rod wiper 278.

[0074] The end of the ball screw 258 remote from the target adapter 260is provided with a threaded portion 280. A pusher bracket 282 is securedto the end of the ball screw 258 by a nylon insert lock nut 284threadably engaged with the end 280 of the ball screw 258. A flat washer286 is located between the pusher bracket 282 and the ball screw 258.

[0075] A slide body 292 is secured to the pusher bracket 282 forreciprocation under the action of the ball screw 258 and the ball nut254 which is in turn actuated by the motor 224 under the control of theCNC system 54. Drive keys 294 are mounted at one end of the slide body292 and is secured thereto by a plurality of threaded fasteners 296. Theslide body 292 is provided with a conventional central bore 298 and isadapted to receive a conventional tool holder, which in turn receives aconventional tool such as a drill, reamer, etc.

[0076] Those skilled in the art will appreciate the fact that the slidebody 292 and tool holder received therein comprise static devices whichare adapted to provide end working functions on rotating stock. Theinternal tool slide assembly 220 is also adapted for use with activeslide components adapted for performing end working functions such astapping, profile work, etc. and also for performing the pick up functionafter the work piece has been severed.

[0077]FIG. 31 illustrates a active tool holder assembly 700 which may beused in lieu of the passive tool holder assembly of FIG. 11 in theinternal slide assembly of the multi-spindle CNC lathe 50 of the presentinvention, if desired. The tool collet holder assembly 700 includes atool holder receiver 702 which is rotatably supported on a sub-frame 704by bearings 706. A motor 708 has as output 710 which drives a drivepulley 712. A belt 714 extends around the drive pulley 712 and a drivenpulley 716 which is operatively connected to the tool holder receiver702. In the use of the apparatus 700, a conventional tool holder ispositioned in the bore 720 of the tool holder receiver 702. The toolholder in turn receives a conventional tool. By means of the motor 708,the tool is adapted for rotation as it is advanced toward and away fromthe rotating stock. By this means the tool may be utilized to provide,for example tapping of the stock.

[0078] Referring to FIG. 9, each slide body 292 has a pair of guideblocks 304 secured thereto by threaded fasteners 306. The guide 304blocks are received in correspondingly shaped, hardened and precisionground, guideways formed in a support body 308 and defined by components307 and 314. Sliding movement of the guide blocks 304, and therefore theand slide bodies 292, is facilitated by the positioning of layers ofpolytetrafluroethylene 310 between the guide blocks 304 and thecorresponding guideways.

[0079] The construction of the guide body 308 will be best understood bysimultaneous reference to FIGS. 5 and 9. The component parts 307 of theguide body 308 comprising the guideways are secured to the cylinder 184by a plurality of threaded fasteners 312. The component parts 314 aresecured by a plurality of threaded fasteners 316. A cover plate 318 ismounted at the end of the guide body 308 remote from the piston 180 andis secured by plurality of threaded fasteners 320.

[0080] Coolant is discharged from flexible nozzle assemblies 322 to theworking area. The nozzle assemblies 322 are selectively mounted indischarged apertures 324 provided in the end plate 318. The apertures324 extend to a passageway 326. Coolant is directed into the passageway326 for discharge from the flexible nozzle assemblies 322 through aninlet port 328 formed in the cylinder 184 Referring now to FIGS. 12through 19, inclusive, the multi-spindle CNC lathe 50 includes aplurality of external slide assemblies 330. Each external slide assembly330 is supported on the wall 114 of the casting 108 of the frame 104 bya support bracket 332 which is secured to the wall 114 by a plurality ofthreaded fasteners 334. Each external slide assembly 330 is adapted tosupport and position a cutting tool 336 relative to rotating stock. Theexternal slide assemblies 330 function to move cutting tools 336 bothtoward and away from the rotating stock and toward and away from thewall 114 of the frame 104, i.e., parallel to the stock.

[0081] Referring to FIGS. 13 and 15, each external slide assembly 330includes a housing 340 which is guided by a circular guide 342 and arectangular guide 344. The guide 342 is mounted on the housing 340 andis slidably supported by bushings 343 mounted on the bracket 332. Theguide 344 is mounted on the bracket 332 and is secured by threadedfasteners 335.

[0082] Referring to FIGS. 15 and 19, a motor 346 is mounted on a motormounting plate 350 and is secured thereto by a plurality of threadedfasteners. The motor mounting plate 350 is in turn supported on amounting plate 352 by a plurality of threaded fasteners 354.

[0083] The motor 346 has an output shaft 356 which is connected to adrive pulley 358. The drive pulley 358 drives a belt 360 which in turndrives a driven pulley 362. The driven pulley 362 is secured on aadapter 364 by an spacer 366. The adapter 364 is rotatably supported onthe plate 116 by a bearing 368 which is mounted in a bearing housing370. The bearing housing 370 is secured in the plate 352 by a pluralityof threaded fasteners 372.

[0084] A ball nut 374 is secured to the adapter 364 by a plurality ofthreaded fasteners 376. Thus, upon actuation of the motor 346 operatingthrough the drive shaft 356, the drive pulley 358, the drive belt 360,and drive pulley 362, the adapter 366, and the spacer 364, the ball nut374 is actuated to rotate relative to the plate 116. A ball screw 378extends through and is operatively connected to the ball nut 374.

[0085] A target adapter 380 is secured to one end of the ball screw 378and has a target 382 mounted on the distal end thereof. A plurality ofproximity sensors 384, 386, and 388, are mounted on a support plate 390which is secured to the motor mounting plate 350 by a plurality ofthreaded fasteners 392. When the target 382 is aligned with one of theproximity sensors 384, 386, or 388, a signal is generated indicative ofthe positioning of the housing 340 of the external slide assemblyrelative to the plate 114 of the frame 104.

[0086] The end of the ball screw 378 remote from the target adapter 380comprises a threaded end portion 394. The ball screw 378 is secured tothe housing 340 of the external slide assembly 330 by a nylon insertlock nut 396. Therefore, upon operation of the motor 346, the ball nut374 functions to actuate the ball screw 378 to locate the housing 340relative to the wall 114. Referring to FIG. 16, the housing 340 issupported for sliding movement toward and away from the wall 114 byguide members 342 and 344.

[0087] The motor 346 operates under control of the CNC system 54 toposition the ball screw 378. The outputs of the proximity sensors 384,386, and 388 are directed to the CNC system 54 which in turn operatesthe motor 346 to position the ball screw 378 in accordance with theprogram being run.

[0088] As is best shown in FIGS. 16 and 17, a motor 400 is mounted atthe end of the housing 340 remote from the cutting tool 336. The motor400 has an output shaft 402 which is connected to a flexible coupling404 which is in turn connected to one end of a ball screw 406. The ballscrew 406 is rotatably supported by bearings 408 and 410 mounted in thehousing 340.

[0089] A ball nut 412 is mounted on and operatively connected to theball screw 406. The ball nut 412 is secured to a tool slide 414 which isslidably supported in the housing 340 by a plurality of threadedfasteners 416. Thus, upon actuation of the motor 400 to rotate the ballscrew 406, the ball nut 412 functions to move the slide 414 andtherefore the cutting tool 336 inwardly and outwardly relative to thehousing 340.

[0090] The motor 400 operates under control of the CNC system 54. Themotor 400 and the slide 414 have associated therewith a target and aplurality of proximity sensors like the target 382 and the sensors 384,386, and 388 associated with the ball screw 308. The CNC system 54receives signals from the sensors to allow control over the positioningof the cutting tool 336.

[0091] Referring particularly to FIG. 18, there is shown a quickdisconnect coupling for the cutting tool 336. The cutting tool 336 issupported on a mounting bar 416 positioned within the slide 414. Thecutting forces resulting from engagement of the cutting tool 336 withrotating stock are taken by a reaction block 418 which is secured to theslide 414 by a threaded fastener 419. The mounting bar 416 and thereforethe cutting tool 336 are normally secured in the position shown in FIG.18 by a retaining bar 420 having a ramp portion 422. A pin 424 ispositioned between the ramp portion 422 and the mounting bar 416 andfunctions to retain the mounting bar 416 and therefore the cutting tool336 in place. A spring 426 normally retains the bar 420 in place.

[0092] A stop 428 is mounted in the housing 340 at the remote end of theslide 414. When the slide 414 is fully retracted under the action of theball nut 412 and the ball screw 406, the bar 402 engages the stop 428.This action compresses the spring 426 thereby relieving the pressureimposed on the pin 424 by the ramp portion 422. This in turn allows thecutting tool 336 and the mounting bar 416 to be disengaged from theslide 414.

[0093] The multi-spindle CNC lathe 50 of the present invention furtherincluded a plurality of spindles 430 of the type illustrated in FIGS.20, 21, and 22. Each spindle 430 is rotatably supported in the spindlecarrier 218 of FIG. 4 by bearings 432 and 434 and is retained therein bythreaded fasteners 436 and 438.

[0094] Each spindle 430 comprises a main body portion 440 having aplanet gear 442 mounted thereon. Spacers 444 and 446 are interposedbetween the planet gear 442 and bearings 432 and 434 respectively. Acollet receiving bore 448 extends through the main body 440 and aconventional self-opening collet 450 is disposed therein. A conventionalcollet aligning mechanism 452 maybe positioned at the collet receivingend of the bore 448. A driving key 454 assures proper alignment betweenthe collet and the spindle.

[0095] The spindles 430 of the present invention comprise a uniquecollet opening, collet closing, and collet releasing mechanism. A glut456 is slidably supported on a glut guide 458 and includes a dog 460which engages a slot 462 formed in a collet actuator 464 mounted on thespindle 430. The collet actuator 464 includes a retainer 466 which issecured by threaded fasteners 468. A spring actuating member 470 isslidably supported within the main body 440 of the spindle 430. A springactuated retainer 472 is slidably supported on the spring actuator 470.

[0096] The collet locked position is illustrated in FIG. 20. At thispoint the glut 456 has been actuated to position the spring actuator 464at its extreme rearward position relative to the collet 450. A series ofwedges 474 have been forced downwardly. This action moves a slider 476rearwardly compressing compensating washers 478, whereby a length astock to be worked (not shown) is securely retained in the collet 450. Adog 480 on the slider 472 is disengaged from the spring retainer 466whereby a plunger 482 is fully extended under the action of a spring484.

[0097] In FIG. 21 the glut 456 is actuated to move the spring actuator464 toward the planet gear 442. The wedges 474 move upwardly under theaction of the compensating washers 478 and centrifugal force. Theretainer 466 approaches but does not quite engage the dog 480, wherebythe pin 482 remains in position. At this point the self-opening collet450 is released sufficiently to permit the repositioning of stockextending therethrough and/or to receive a new length of stock havingthe same dimensions as the previously engaged stock.

[0098] In FIG. 22 the glut 456 is actuated to move the spring actuator464 to its extreme position. At this point the spring 484 issubstantially compressed due to actuation of the pin 482 by the camactuator 470 and the engagement of the dog 480 with the retainer 466.This aligns a detent 486 with a retaining ball 488 to allow the ball 488to move upwardly, thereby permitting the removal of the collet 450.

[0099] Collet removal is indicated when a different size or type ofstock is to be retained by the collet 450 for rotation by the spindle430. Removal of the collet 450 may be effected either manually orautomatically through the use of conventional collet removal andreplacement apparatus. FIG. 23 illustrates a glut actuator 490 useful inthe practice of the present invention to operate the glut 460 shown inFIG. 20. The glut actuator 490 is mounted on the wall 116 of the casting108 and is supported thereon by a mounting plate 492 which is secured tothe wall 116 by a plurality of threaded fasteners 494. A glut actuator496 is secured to a movable housing 498 which is slidably supported on aguide rod 500. The guide rod 500 is secured to the mounting plate 492 bya threaded fastener 502. A piston 504 is fixedly mounted on the guiderod 500, and is provided with seals 506. An inner piston 508 is slidablysupported on the guide rod 500 and is provided with seals 510. An outerpiston 512 is likewise slidably supported on the guide rod 500 and isprovided with seals 514.

[0100] The pistons 504, 508, and 512 divide the housing 498 into fourchambers 516, 518, 520, and 522. Hydraulic fluid inlet and outlet ports526, 528, 530, and 532 extend to the chambers 516, 518, 520 and 530,respectively. Chamber 516 is secured against leakage by seals 534, andchamber 522 is secured against leakage by seals 536.

[0101] It will thus be understood by those skilled in the art that byselectively admitting pressurized hydraulic fluid to one of the chambers516, 518, 520, and 522, and by simultaneously draining hydraulic fluidfrom the remaining chambers, the housing 498 and therefore the glutactuator 496 maybe selectively located in any of four positions relativeto the guide rod 500 and the wall 516. In this manner the glut actuator490 of FIG. 23 functions to position the glut 460 of FIG. 20, therebyselectively engaging, disengaging, or releasing the collets 450 of themulti-spindle CNC lathe 50 of the present invention. The fourth positionof the glut actuator 490 is used to allow indexing of the spindlecarrier 218.

[0102] Referring to FIG. 19, the multi-spindle CNC lathe 50 is shown ashaving eight gluts 456, eight glut guides 458, eight dogs 460, and eightglut conductors 490. This is to demonstrate the use of such componentsat any of the work stations and in as many numbers as needed for theparticular application of the invention. Usually, no more than two glutsand glut actuators will be needed.

[0103] The spindle carrier 218 of FIG. 4 is further illustrated in theFIG. 24. Multi-toothed coupling portion 540 having teeth 542 formed atequally spaced intervals therearound is secured between opposed bodyportions 544 and 546. Coupling portion 540 is aligned by means of adowel 548 and is secured in place by means of threaded fasteners 550.The body portions 544 and 546 are in turn secured together by threadedfasteners 552.

[0104] The spindle supporting bearings 434 illustrated in FIGS. 20, 21,and 22 are received in a bearing receiving cavity 554 formed in bodymember 546. The bearings 434 are secured in place by a plate 556 whichis retained by the threaded fasteners 438. The bearings 432 asillustrated in FIGS. 20, 21, and 22 are received in a bearing receivingcavity 558 formed in the body member 544. The bearings 432 are securedby a plate 560 which is secured in place by the threaded fasteners 436.

[0105] Referring again to FIG. 24, the body portions 544 and 546 arepreferably secured in place prior to the machining of the bearingreceiving cavities 554 and 556, thereby assuring precise alignmentbetween the cavities. It will be appreciated that it is occasionallynecessary to disassemble the body portions 544 and 546. To this endthere is provided an alignment ring 562 having extended profile portions564. The profile portions comprise segments of approximately 60 degreeswhich are in turn separated by vacant segments of approximately 60degrees. By means of the profile portions 564 of the alignment ring 562,the body portions 544 and 546 of the spindle carrier 218 may beseparated and reassembled without loss of alignment between the bearingreceiving cavities 554 and 558.

[0106] A sun gear 570 is rotatably supported within the spindle carrier218. The sun gear 570 is rotatably supported by bearings 572 which areretained by a plate 574. The plate 574 is in turn retained by threadedfasteners 576.

[0107] The sun gear 570 has an internal spline 578 which engages in theinternal spline 579 of the drive shaft 166 FIG. 4. In this manner thesun gear is rotated under the action of the spindle drive motor 154. Thesun gear 570 engages the planet gears 442 of the spindles 430, wherebythe motor 154 functions to rotate the spindles at a predetermined speed.

[0108] The spindle carrier 218 is secured to the tubular ram 182 bymeans of the threaded fasteners 210 which engage complementary threadedapertures 580 formed in the body portion 546. Thus, upon actuation ofthe piston 180, the positioning of the spindle carrier 218 is shiftedlongitudinally relative to the frame 104.

[0109] Referring to FIG. 26, the casting 108 comprising the frame 104has a multi-toothed coupling portion 582 secured therein by threadedfasteners 586. The coupling portion 582 comprises a plurality of teeth588 which are inverse to the teeth 542 of the coupling portion 540 ofthe spindle carrier 218. Thus, when the piston 180 is actuated to movethe ram 182 toward the casting 108, the teeth 542 of the spindle carrier218 engaged the teeth 588 of the coupling portion 582 on the casting 108to secure the spindle carrier 218 against rotation relative to the frame104 of the multi-spindle CNC lathe 50. Conversely, when the piston 180is actuated to move the ram 182 away from the casting 108 the teeth 542on the spindle carrier 218 are disengaged from the teeth 588 of thecoupling portion 582 on the casting 108, whereupon the spindle carrier218 is adapted for indexing relative to the frame 104 of the lathe 50.

[0110] The frame 104 is provided with a bearing member 590. The bearingmember 590 has a precisely machined internal surface 592 which rotatablysupports the spindle carrier 218 for indexing. To this end the lowersegment of the bearing surface 214 is provided with a layer ofpolytetrafluroethylene 594 to facilitate rotation of the spindle carrier218 relative to the bearing ring 590.

[0111] The multi-spindle CNC lathe 50 is provided with a plurality ofstock carrier assemblies 600 which are best illustrated in FIGS. 27 and28. Each stock carrier assembly 600 includes an inner stock carryingtube 602 which extends through one of the spindles 430 and is supportedtherein for rotation with the collet 450 received in and rotated by thespindle 430. Each tube 602 is secured to a nut 604 which is threadedlyengaged with the spindle 430, thereby securing the tube 602 for rotationwith the collet 450. The use of a stock carrying tube adapted forrotation with the stock received therein comprises an important featureof the present invention and is a significant departure from the priorart.

[0112] Throughout a significant portion of its length the tube 602extends through a stationary tube 606. The tube 606 is provided with aconventional closure 608 located at the end thereof remote form thespindle 430. The particular closure 608 illustrated FIG. 27 is of thebayonet variety and is provided with a handle 610 which is movedinwardly to release the closure 608 for the insertion of stock into andthrough the tubes 606 and 602. At all other times the closure 608remains positioned as shown in FIG. 27 to seal the interior of the tube606 against leakage of coolant therefrom.

[0113] The rotating tube 602 has a plurality of apertures 612 formedtherein to permit the flow of collant out the tube 602 into the tube606. The tube 606 extends to a seal 614 which prevents leakage ofcoolant from the end of the tube 606 remote from the closure 608. Asecondary seal 616 is mounted on the seal 614 and extends along the tube602 further to prevent leakage of coolant.

[0114] Each tube 606 is further provided with fixtures 618 and 620 whichfunction to admit coolant into the tube 606. Whenever it is desired toadvance the position of the stock located within and rotating with thetube 602, the pressure of the coolant within the tube 606 is increased.It will be understood that one end of the stock is situated within theassembly comprising the tubes 602 and 606, and is therefore subject tothe application of an endwise force resulting from the increase incoolant pressure. However, the opposite end of the stock is situatedwithin the collet and is therefore not subject to the increased pressureof the coolant within the tubes 602 and 606. By this means there isprovided an endwise force on the stock which pushes the stock throughthe collet 450 without requiring the use independent stock advancingmechanisms. The presence of the coolant within the tubes 602 and 606also provides significant vibration damping and noise reduction ascompared with prior art stock advancing mechanisms.

[0115] The stock carriage mechanism of the multi-spindle CNC lathe 50 isillustrated in FIG. 29. The stock carriage tubes 602 and 606 of thestock carriage assembly 600 are supported on a carriage assembly 622.Rings 624 are provided at each end of a stock carriage housing 626.Rollers 628 are provided on the carriage assembly 622 and engage therings 624. By this means the carriage assembly 622 and therefore thestock carriage assembly 600 is adapted for revolution about the centralaxis 632 of the multi-spindle CNC lathe 50.

[0116] An indexing mechanism 640 for the multi-spindle CNC lathe 50 isillustrated in FIG. 30. A motor 642 drives an indexer 643 which has anoutput 644 that drives a drive pulley 646. A belt 648 extends around thedrive pulley 646 and functions to actuate a driven pulley 650 under theaction of the motor 642 and the indexer 643. The driven pulley 650 isconnected to a rotator plate 652 which is connected to the carriageassembly 622 by a plurality of threaded fasteners 658. Thus, uponactuation of the motor 642 and indexing 643, the carriage assembly 622and the stock carriage tubes mounted thereon are revolved around theaxis 632.

[0117] A spider 656 is mounted to the assembly 622 for rotationtherewith under the action of the motor 642 and the indexer 643. Thespider 656 comprises a plurality of pins 660 each having opposedspherical ends 662. The spherical ends 662 of the pins 660 are receivedin bores 664, thereby accommodating a predetermined amount ofmisalignment between the assembly 622 and a connector 666 which issecured to the spindle carrier 218 by means of a plurality of threadedfasteners 668. Thus, upon actuation the motor 642 functions not only torotate the assembly 622 but also to rotate the spindle carrier assembly218 simultaneously therewith.

OPERATION

[0118] In the operation of the multi-spindle CNC lathe 50, one or moreof the closures 608 is disengaged to permit the insertion of stock intothe tube 606 and the tube 602 of the stock carrier assembly. The glutactuator assembly 490 is then actuated to operate the glut 460 to openone or more of the collets 450. Stock is initially positioned manually.Thereafter, pressure of the coolant within the tubes 602 and 606 of thestock carrier assembly is selectively increased, whereupon the stock isadvanced through the corresponding collet 450 until it properlypositioned.

[0119] Indexing of the stock relative to the tools of the multi-spindleCNC lathe 50 begins with actuation of the piston 180 to move the ram 182rightwardly (FIG. 5) thereby disengaging the teeth 542 of the couplingportion 540 of the stock carrier 218 (FIG. 24) from the teeth 582 of thecoupling portion 584 which is secured to the frame 104 (FIG. 26). Theindexing motor 642 (FIG. 30) is then actuated to index the carriageassembly 622 and therefore the tubes 602 and 606, and also the stockcarrier 218 having the spindles 430 and the collets 450 mounted thereon.This action cause the stock, the tube 602 and 606, the spindles 430, andthe collets 450 to revolve about the axis 632 of the multi-spindle CNClathe 50 until the stock is properly positioned relative to the frame.

[0120] The internal slide assemblies 220 of the multi-spindle CNC lathe50 are mounted on the guide body 308 which is secured to the wall 112 ofthe casting 106 of the frame 104. Therefore, as the stock is indexedunder the action of the motor 642, the internal slide assemblies do notmove, but instead remain stationary and in position to engage the nextindividual piece of stock which is aligned therewith.

[0121] Likewise, the external slide assembly 330 are supported onsubframes 332 which are secured to the wall 114 of the casting 108 ofthe frame 104 by threaded fasteners 334. Therefore, the external slidesassembly 330 do not move as the stock in indexed under the action of themotor 642, but instead remained positioned for engagement with the nextpiece of stock which is aligned therewith.

[0122] An important feature of the present invention comprises the factthat the external slide assembly 330 are adapted to move the tools 336not only toward and away from, that is, perpendicular to the rotatingstock, but also along the length of, that is parallel to the stock. Thetools 336 do not comprise forming tools, but instead comprise generalpurpose metal working tools which maybe utilized to form any desiredshape in the external surfaces of the stock pieces. It is therefore notnecessary to remove and replace the tools 336 when adapting themulti-spindle CNC lathe 50 of the present invention to the manufactureof a different product.

[0123] This in turn means that the multi-spindle CNC lathe 50 of thepresent invention is readily adapted to the Just In Time, or JIT,manufacturing philosophy in that the lathe 50 may be utilized tomanufacture a small number of parts and to have the parts available atthe precise moment that they are needed in subsequent manufacturingoperations. The multi-spindle CNC lathe 50 of the present invention isalso readily adapted to the Statistical Process Control, or SPC,manufacturing philosophy whereby wearing of the tools utilized in theinternal slide assemblies 220 and the external slide assemblies 330 isconstantly monitored and adjusted for by actuating the slide assemblies220 and 330 to assure manufacturing tolerances which are well within theacceptable range.

[0124] After all of the tools comprising the internal slide assemblies220 and all of the tools comprising the external slide assembly 330 havecompleted their respective functions, the tools are disengaged from therotating stock. At this point the piston 180 is actuated to disengagethe teeth 542 of the stock carrier 218 from the teeth 582, whereupon themotor 642 is actuated to index the stock into alignment with the nextsuccessive work station. As will be understood by those skilled in theart, one or more of the spindles comprising the multi-spindle CNC lathe50 comprises a cutoff station, wherein the finished work is disengagedfrom the stock. Upon cutoff, of the stock is selectively advancedthrough the respective collets under the action of increased pressure inthe coolant in the associated tubes 602 and 606.

[0125] All of the component parts of the multi-spindle CNC lathe operateunder the control of the CNC system 54. In this manner there isfacilitated the use of general purpose cutting tools, rather thanforming tools, which in turn facilitates the JIT manufacturingphilosophy. Likewise, the CNC system facilitates the SPC manufacturingphilosophy by constantly repositioning the cutting tools to accommodatewear.

[0126] Those skilled in the art will appreciate the fact that in theoperation of the multi-spindle CNC lathe of the present invention, thetwo servo mechanisms comprising each external slide assembly operatesimultaneously in order to form the complex configurations which aretypically fabricated on single spindle and multi-spindle legs.Preferably, each internal slide assembly 220 operates simultaneouslywith its corresponding external slide assembly 330 in order that themulti-spindle CNC lathe 50 can function at maximum efficiency. It willbe understood, however, that a particular internal slide assembly 220and its corresponding external slide assembly 330 can operatesequentially depending upon the requirements of particular applicationsof the invention.

[0127] Referring to FIG. 34, there is shown a length of bar stock 680which is sequentially formed into four entirely different piece parts682, 684, 686, and 688 utilizing the multi-spindle CNC lathe of thepresent invention. The piece parts 682, 684, 686, and 688 are formed atthe same work station with the fabrication of the piece part 684beginning immediately after the completion of the piece part 682, etc.and without the necessity of changing cutting tools or changing the setup of the multi-spindle CNC lathe 50. Referring to FIG. 35, a length ofoctagonal bar stock 690 is fabricated into entirely different pieceparts 692 and 694. Again, the manufacture of the piece part 694 beginsimmediately upon the completion of the piece part 692 without changingcutting tools and without changing the set up of the multi-spindle CNClathe 50.

[0128] Although preferred embodiments of the invention have beenillustrated in the accompanying Drawings and described in the foregoingDetailed Description, it will be understood that the invention is notlimited to the embodiments disclosed but is capable of numerousrearrangements, modification, and substitutions of parts and elementswithout departing from the spirit of the invention.

What is claimed is:
 1. A method of forming a single length of bar stockinto two different parts including the steps of: providing a length ofbar stock having an axis and a leading end including a first segment anda second segment; rotating the length of bar stock about its axis;providing a forming zone; selectively advancing the length of bar stockin a predetermined direction along its axis until the leading end of thelength of bar stock is located in the forming zone; providing a firstsingle point cutting tool located in the forming zone; providing a firstservo mechanism for selectively advancing and retracting the firstcutting tool along a path parallel to the axis of the rotating length ofbar stock; providing a second single point cutting tool located in theforming zone; providing a second servo mechanism for selectivelyadvancing and retracting the second cutting tool radially relative tothe rotating length of bar stock; providing a third servo mechanism forselectively advancing and retracting the second cutting tool along apath parallel to the axis of the rotating bar stock; providing acomputer numeric control system for simultaneously operating the first,second, and third servo mechanisms; causing the computer numeric controlsystem to simultaneously operate the first, second, and third servomechanisms to advance and retract the first and second cutting tools inaccordance with a first predetermined sequence of instructions to formthe first segment of the leading end of the rotating length of the barstock into a first predetermined configuration; thereafter advancing thelength of bar stock along its axis until the second segment of theleading end of the length of bar stock is positioned in the formingzone; immediately thereafter causing the computer numeric control systemto simultaneously operate the first, second and third servo mechanismsto advance and retract the first and second cutting tools in accordancewith a second predetermined sequence of instructions to form the secondsegment of the leading end of the rotating length of bar stock into asecond predetermined configuration which is substantially different fromthe first predetermined configuration.
 2. A method of forming a singlelength of bar stock into two different parts including the steps of:storing two sets of operating instructions, the first set of operatinginstructions corresponding to configuration of a first part to be formedand the second part of operating instructions corresponding to theconfiguration of a second part to be formed, the configuration of thefirst and second parts to be formed to be substantially different;providing a length of bar stock having a longitudinal axis and a leadingend comprising axially spaced first and second segments; rotating thelength of bar stock about its longitudinal axis; providing a formingzone; selectively advancing the length of bar stock in a predetermineddirection along its longitudinal axis until the first segment of theleading end of the length of bar stock is positioned in the formingzone; providing a first single point cutting tool located in the formingzone; providing a servo mechanism for selectively advancing andretracting the first single point cutting tool along a path extendingparallel to the axis of the rotating length of bar stock; providing asecond single point cutting tool located in the forming zone; providinga second servo mechanism for selectively advancing and retracting thesecond single point cutting tool radially relative to the rotatinglength of bar stock; providing a third servo mechanism for selectivelyadvancing and retracting the second single point cutting tool along apath parallel to the axis of the rotating length of bar stock;simultaneously operating the first, second and third servo mechanisms inaccordance with the first set of instructions to advance and retract thefirst and second single point cutting tools in accordance therewith toform a first segment of the leading end of the rotating length of barstock into the first predetermined configuration; thereafter advancingthe length of bar stock along its longitudinal axis until the secondsegment of the leading end of the length of bar stock is positioned inthe forming zone; immediately thereafter simultaneously operating thefirst, second, and third servo mechanisms to advance and retract thefirst and second single point cutting tools in accordance with thesecond set of instructions to form the second segment of the leading endof the rotating length of bar stock into the second configuration.